generally to a magnetic head for a
This invention relates perpendicular- recording system, and more particularly to a thin film magnetic head which is especially adapted for recording on double-sided/double-layer disc or media, and a process for forming that head.
In conventional magnetic recording media, data is recorded by magnetizing the magnetic layer of the media in a longitudinal direction parallel to the direction of relative movement between the magnetic medium and the transducer, or head, positioned adjacent to the medium. In perpendicular recording, data is recorded by magnetizing the magnetic recording layer in the direction perpendicular to the surface of the medium.
Magnetic recording transducers generally fall into two classes: ring-type heads that employ magnetic material generally in the shape of a ring for defining a magnetic path, the ring having a gap therein for defining the location of the data recorded, and single pole piece heads that employ an elongated strip of high saturation flux density material to link the magnetic flux being sensed by the head with an operatively associated coil. In ring-type heads, as noted above, the resolution of the head is a function of the length of the gap, whereas in single pole piece heads, the resolution is a function of the thickness of the pole piece at its tip.
Ring-type heads have long been used in longitudinal recording and have also been proposed for use in perpendicular recording. However, since a major advantage of perpendicular recording is the ability to read and write data at high density, the use of ring-type heads in perpendicular recording has not been considered advantageous because the pulse widths obtained with ring-type heads tend to lead to peak shift problems at high density. Further, ring-type heads often provide asymmetric pulse shapes and in general give rise to difficulties in reading and writing at ultra high densities. Ring-type heads as now known cannot be used with all perpendicular recording media.
Single pole piece heads offer the advantage of high resolution if the pole piece is made by thin film deposition techniques. With thin film deposition, pole pieces of less than one micron thickness can be obtained, which would enable the head to read information stored at very high densities. However, there has not yet been developed commercially acceptable methods of making and using a high volume thin film single pole piece head for perpendicular recording.